Sometimes the resume nails your application—and sometimes your cover letter gets you in the door. How do you know which to emphasize for a given application?

Though I believe you should ensure you’ve got both pieces on point when you apply, no matter the position or company, you can determine where to put your focus via the following litmus test:

• If you will send your application to a recruiter or into an automated human-resources system with on-line forms—and probably if sending it straight to the human-resources department in general, via whatever method—your application is all about the resume.

• If you will apply directly to the hiring manager or if you believe that the decision maker for the hire will get your entire application—a likelihood in smaller companies, where all submissions get vetted in full by the hiring manager, even if the original send-to address or instructions appears generic—your application is all about the cover letter.

Let’s talk about the latter scenario.

Yeah, you know: The requested item in the job posting that you shrug off with two sentences referencing your attached resume or something canned with the relevant job title (I hope) pasted into the body of the text (let’s assume you ensure you pasted it in the same font and point size, at least).

When appealing directly to a hiring manager, your resume serves simply to back up what you’ve said in your cover letter—especially if the position falls into what people now call “knowledge work,” a term used for most professional positions. In this case, you should consider your resume as your supporting evidence—the footnotes and appendix to your main argument.

Because in this type of case and for this type of role, if you really want the job, you’d better pull out all the stops in your cover letter. I’ve hired several people based on their cover letters alone—and I know several other business leaders who have done the same.

Format

Learn how to format an honest-to-goodness business letter. Then employ what you’ve learned. Even if you intend to put your cover letter in the body of an e-mail (and I have no qualms about going this route), you can at least format it clearly, cleanly, and correctly.

Further, do everything you can to get the hiring manager’s name. Do not write a cover letter to “Sir/Madame.” (People last used these terms for the general population two centuries ago.) Do not send the letter “To Whom It May Concern.” (If the company has decided to hire, the hiring manager has passed the state of “maybe” caring.)

Besides, these phrases look lazy.

Make Your Case

Your cover letter is your first impression. Without a good one, you may never get a call or meeting. Don’t miss your chance to plead your case.

Realize that no job is exactly like any other job—even if they have the same title in the same industry. Companies differ. Managers and departments differ. Nuances of job descriptions differ. People don’t create roles with cookie cutters, so your cover letter shouldn’t take template form, either. Nothing turns off a hiring manager more than a canned cover letter. (And yes, we can tell.)

For each position, start fresh. Research the company, the department or division, the job, and the hiring manager. Show what you know of the company, its work, and the open role and illustrate how your experience and immediate and long-term professional goals align with the position. Show that you understand the role’s needs and the company’s expectations. Show your personality and your approach to the work.

If your application targets a position a bit off the track of your career, don’t shy away from applying if you truly want the role and know you could nail it, given the chance: Just address the pivot in your cover letter clearly and crisply.

This advice counts as well for any applications you send for positions requiring experience or particulars that you don’t quite meet (the company may make an exception to the requirement if you make a good case) and if you see any possible red flags in your resume that might disqualify you without explanation.

Possible red flags to address could include gaps in your work history, shorter-than-typical terms in recent positions, or a mailing address that doesn’t align with the work location. (In the latter case, the hiring manager may pass on your resume if the company hasn’t provided a relocation budget—a nonissue if you plan to relocate already on your own dime.)

Doing anything less than writing a clear, crisp case statement in your cover letter appears apathetic and careless.

And no one seeks to hire lazy, sloppy people.

The Details Matter

I don’t know a single hiring manager who would say she doesn’t want a high level of detail orientation. She expects it, even if she doesn’t specifically request it in the job description.

So get the company’s name and the job title correct—especially the spelling, spacing, and capitalization. Ensure the consistency of the letter’s font style and size. Ensure you’ve made all the text black or dark gray. (Yes, this advice seems obvious. Yet I’d guesstimate that three out of five applications we receive at FrogDog contains one of these errors. Yes, really.)

And don’t rely on spell check—read, reread, and have someone else read and reread your letter. Consider leaving it for a bit and returning with fresh eyes. A few hours or overnight won’t kill your chances—especially when you have a zinging cover letter.

What impresses you most when reviewing applications?